Comment by Glawhantojar

These can be found on the ground around 49.81 65.27 in the Vale of Eternal Blossoms, there are several Ancient Mogu Spirit's hanging around fighting Echo's of Pandaren Monk's. As long as you don't engage them, or get too close they will not actively agro you so you can gather in peace.

When you gather one you get the Lushroom Dust buff, which increases damage done and damage taken by 10% per stack, to a max stack of 5.